1. Field of the Invention
The present invention generally relates to a technology for preventing degradation of data recorded in a recording medium.
2. Description of the Related Art
Recently, with the development and spread of broadband communication or digitalized-home-electric appliances, higher and higher capacity of a hard disk drive (HDD) has been increasingly required. Although there have been various methods for increasing memory capacity of the HDD, because a package for storing a magnetic disk is limited in size, a method for increasing a recording density of the magnetic disk is more effective. For example, a perpendicular recording method is known as one of the methods for recording data with accuracy to the magnetic disk having higher recording densities.
However, with the perpendicular recording method, when data is recorded repeatedly in a recording area, data recorded in a neighboring track of the recording area (i.e., servo data used for controlling a position of a magnetic head or user information) gets degraded, thereby making reproduction of the data difficult.
“High-Density Perpendicular Recording Technology”, Takuya Uzumaki, published at http://magazine.fujitsu.com/vol56-4/paper04.pdf, discloses a technology for preventing data recorded on a magnetic disk from degradation by coating the magnetic disk with magnetic layer called soft under-layer (SUL) to generate larger magnetic field with magnetic interaction between a magnetic head and the SUL.
However, with the conventional perpendicular recording method, it is required to substantially improve configurations of the magnetic disk and the magnetic head (for example, it is necessary to provide the SUL on the magnetic disk in the above technology), thereby considerably increasing costs for producing the HDD. Thus, there is a need for a technology for preventing data recorded on the magnetic disk from degradation caused by recording data repeatedly without substantially improving the configurations of the magnetic disk and the magnetic head.